Vehicle Driving Force Control Device Torque Calculation Stability
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Solution Overview
Problem
Existing driving force control devices for vehicles with automatic transmissions face instability due to incorrect calculation of engine torque when there is a failure in the transmission, leading to excessively large torque output, especially when the actual gear ratio differs significantly from the instructed gear ratio.
Innovation Solution
A driving force control device that calculates output torque using either the actual gear ratio or the gear ratio instruction value based on the detected abnormality, selecting a larger gear ratio during failures to prevent excessive torque calculation and ensuring stability by using the gear ratio instruction value during normal operations to prevent fluctuations in driving force control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the actual gear ratio is used for torque calculation, then the torque calculation reflects the true transmission state, but control stability deteriorates due to fluctuation in revolution speed or sensor accuracy
Solution Approach 1:
The patent introduces an intermediary mechanism by comparing two gear ratio values (instruction value and calculated value) and selecting the appropriate one based on their agreement. This intermediary selection process mediates between the precision of actual measurement and the stability of control, using the instruction value as a stable reference when measurements fluctuate.
Solution Approach 2:
The system implements feedback by continuously monitoring the agreement between the gear ratio instruction value and the calculated gear ratio value. When these values disagree beyond a threshold, the system feedbacks to use the instruction value instead, thereby stabilizing control against measurement fluctuations.
2Stability of the object's composition
If the gear ratio instruction value is used for torque calculation, then control stability is maintained, but accuracy deteriorates when transmission failure occurs and actual gear ratio deviates from instructed value
Solution Approach 1:
The patent applies dynamics by making the gear ratio selection adaptive rather than fixed. The system dynamically switches between using the instruction value and the calculated value based on real-time agreement assessment, allowing it to optimize between stability and accuracy according to actual transmission conditions.
Solution Approach 2:
The system changes the parameter used for torque calculation (gear ratio value) based on the agreement between instruction and calculated values. When agreement is poor, it changes from using the calculated value to using the instruction value, thereby adapting to transmission anomalies.
3Measurement precision
If the calculated gear ratio is used during transmission failure, then the true gear ratio is reflected, but excessive torque is calculated when actual gear ratio is much larger than instructed value
Solution Approach 1:
The patent applies preliminary anti-action by preemptively checking the agreement between gear ratio values before using the calculated value for torque calculation. When disagreement is detected (indicating potential transmission failure), the system preemptively switches to using the instruction value, thereby preventing the harmful effect of excessive torque calculation before it occurs.
Data Source
AI summary
A powertrain manager executes a program including the steps of: reading an instruction gear ratio kgear(1) for transmission control; calculating an actual gear ratio kgear(2); determining that failure of an automatic transmission has occurred on a low gear side if relation of kgear(1)<{kgear(2)/α} or kgear(1)<{kgear(2)−β} is satisfied; and substituting larger one of kgear(1) and kgear(2) into a gear ratio for operation.